[clang] [llvm] Explicit types in cbuffer layouts (PR #156919)

[Justin Bogner via llvm-commits]

bogner wrote:

Updated with typed GEPs and padding types if you want to take a look at what code we're generating, but the diff is kind of unreadable at the moment. I'll be cleaning this up and getting things ready for staging next.

https://github.com/llvm/llvm-project/pull/156919